Sow seeds in damp compost, wait for growth. I saw that some seeds of Mirabilis jalapa were included in a "sprinkle on the ground and rake in" mixture I planted the other day.

I used to grow these and found they were almost hardy. The plants make a little tuber that you can try overwintering - dig it up in autumn and store frost free like a dahlia.

I never had problems with germination of seeds.